1. Prior Arts
Spergualin is a compound isolated from a culture filtrate of a spergualin-producing bacterium belonging to the genus Bacillus by Umezawa et al. and represented by the following formula: ##STR2##
This compound is expected to be useful as an anti-malignant tumor agent, since it is effective in the treatment of mouse leukemia L1210, mouse leukemia EL-4, Ehrlich carcinoma and sarcoma 180 (cf. U.S. Pat. No. 4,416,899).
As the results of the subsequent studies, there have been synthesized a number of spergualin derivatives, including those to be used in the present invention, having an improved anti-tumor activity or an elevated stability (cf. U.S. Pat. Nos. 4,518,532, 4,529,549, 4,556,735, EP 241797). It has been further disclosed that these compounds have an intense immunosuppressive effect (cf. EP-A.sub.2 -18592).
Thus they are expected to be effective as an immunosuppressive agent in organ transplantation or in the treatment of autoimmune diseases.
2. Problems to be Solved by the Invention
Chemotherapy and radiotherapy have been widely applied to the treatment of various diseases. However these therapeutics would frequently cause serious side effects, which makes it unavoidable to stop the treatment.
Therefore it is highly valuable to prevent or relieve the side effects caused by these therapeutics. However there has been known no agent capable of relieving the side effects caused by chemotherapy or radiotherapy.